<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            margin: 0;
            padding: 0;
            list-style: none;
        }

        ul li {
            float: left;
            color: yellow;
            font-size: 5rem;
        }
    </style>
</head>
<body>
    <ul>
        <li>☆</li>
        <li>☆</li>
        <li>☆</li>
        <li>☆</li>
        <li>☆</li>
    </ul>

    <script src="./lib/jquery.js"></script>
    <script>
        $("ul li").hover(function () {
            $(this).html("★").prevAll().html("★")
        }, function () {
             $(this).parent().children().html("☆")
        })
    </script>
</body>
</html>